Ozonolysis of Lignin: From Extensive Degradation to Selective Ring-Opening Oxidation

Despite its potential as a renewable feedstock, lignin, a major component of plant cell walls and a by-product of the pulp and paper industry, has long been underutilized. Historically, pulp mills employed ozonolysis, a powerful oxidative process, to delignify cellulosic fibers and break down lignin. The ability of this technique to modify lignin structures has attracted attention in recent years, creating opportunities for the development of novel lignin-based materials with improved functions. This review revisits the use of ozone as a bleaching agent and bridges its historical role in pulp processing with its emerging potential as a selective oxidative tool for lignin modification in materials chemistry. We discuss the fundamental chemical processes, significant developments in ozonolysis technology, and its potential to functionalize sustainable biomaterials. We also give our perspectives on the present obstacles and potential opportunities for ozonolysis optimization in lignin valorization.